This invention relates to a motor-driven treadmill for providing a variable level of exercise, and more particularly to a treadmill of that type wherein the level of exercise is responsive to the performance of a person using the treadmill.
Treadmills which are capable of varying the level of exercise, by varying the speed and/or slope of the treadmill by means of controls operated by the user, are known in the art.
Also known in the art are treadmills which are capable of automatically varying the speed and/or slope of the treadmill according to a predetermined program, based on either (i) the amount of time elapsed since the start of the program, or (ii) the total amount of user effort as determined by elapsed time as well as treadmill speed and/or treadmill slope.
Ogden et al. U.S. Pat. No. 4,635,928 has hand rails with a speed control mounted on one of the rails.
Pittaway et al. U.S. Pat. No. 4,749,181 incorporates a central processing unit which monitors various speed-related parameters and shuts down the treadmill if the parameters indicate a malfunction.
Sweeney, Sr. et al. U.S. Pat. No. 4,842,266 incorporates a microprocessor which provides pre-programmed speed variation as well as a display indicative of the performance of the user.
Kuo U.S. Pat. No. 4,865,313 relates to a mechanical arrangement for speed changing purposes.
Lin U.S. Pat. No. 4,917,375 relates to a mechanical arrangement for manually changing treadmill speed by turning a handle bar.
While these treadmills allow walking or running exercise in a confined space, they also require the person exercising to match the motion of the moving surface, at whatever speed and/or slope has been pre-programmed into the treadmill or set by the user. Since the apparatus thus "controls" the user, a risk of injury exists.
An object of the present invention is to provide an improved treadmill which is more convenient and safe to use than those of the prior art, and which varies the degree of difficulty of exercise thereon according to the actual current performance of the user.
Another object of the invention is to provide improved exercise apparatus which adapts the speed and/or slope of a moving medium traversed by the user to the exercise capability of the user.
A further object of the invention is to provide a treadmill which is capable of more accurately determining the energy expended by the user, as compared with prior art treadmills.
A still further object of the invention is to provide a treadmill which is capable of determining the cadence and gait of the user.